Diode Definition and 555 Threads

Question requires a definition and typical values during normal/abnormal operation (Power dissipation of 20A Diode with 1V across it) Have got definition no problems, but am struggling with typical values. Power dissipated would be in watts, but in order to provide that you would need...

New to the forum, I'll say "Hi," first :) Homework Statement Have a physics assignment to hand in. Very simple experiment - increase the voltage in a circuit and measure the current/voltage across the diode in forward and reverse. The problem comes with dealing with infinity in some of the...

Dear Experts,o:) I have recently soldered some diodes to maintain a constant voltage. This i learned from this nice forum. But when using it, the diode can become quite warm. My doubt is, when diodes become warm to touch, like about 60 degrees celsius , is it something wrong with the...

the depletion region is resposible for voltage drop all that is fine but in forward bias there is no depletion region hence there can be no voltage drop but it is mentioned in my book that the voltage will drop by .7 volt how come this can happen also i have many doubts in transistor...

So the current through a diode as a function of applied voltage is: I = I0 [ exp( V q / KB T) - 1 ] where V is the voltage (independent variable), q is the charge of the electron (constant), T is temperature (constant over each trial), I0 is some parameter that's measured to be really tiny (I...

guys I'm looking for general purpose diode like 1N4148. it should be small.(smaller than 1n4148). surface mount solution is not going to work as they are very expensive. I'm working on a circuit and need to use parts small as possible. i use 1/8w resistors and 1n4148 as diodes as they are...

what is the mean of "slope resistance" of zener diode? Its parallel to diod or series?

Homework Statement Attached is the homework problem I'm having difficulty with. I need to sketch vout for the circuit, assuming the diode ON voltage is 0.6 V. I'm stuck at how to begin this problem. Homework Equations The Attempt at a Solution It's only the 2nd week of class so...

Homework Statement List at least five methods by which a transistor can be used as a diode. Homework Equations N/A The Attempt at a Solution I know three configurations viz. Collector Emitter Short, Collector Base short and Base emitter Short.. What would be the remaining two...

Homework Statement Find Voltage/Current across each diode: ----R--- |...| V...D |... | ----R--- Repeat 50x until...

http://i30.tinypic.com/2i2r9i.gif

I am just beginning to learn about diodes and I was wondering if there are any tips to making the correct guess for the diode model. For our class, we use a model that consists of four regions instead of the simple on/off model. basically to figure out what the diode is doing, we insert the...

http://img12.imageshack.us/img12/7084/helpphg.jpg In the image shown above, how is the average diode current calculated? This is an old homework assignment and I'm taking notes. I would appreciate any help. Thank you.

Hello, I made a circuit to convert AC to DC. It looks like this. http://openbookproject.net/electricCircuits/Semi/03267.png My output DC voltage is around 5 volts. Could someone please explain to me how I could figure out the current running through each of the phases at a given time given a...

This post is similar to the one that I made the other day. There are two problems that I am having trouble understanding. The link is below: http://img510.imageshack.us/img510/4396/diodeproblem.jpg They are numbered 4-5 (Ignore 3) . Once again I know the predictions are correct , because I did...

The link provided shows two cases of reverse bias Diodes. From my understanding a reverse bias diode is supposed to block the voltage from reaching the output. So from the following picture wouldn't both of the outputs be 0v. I know that the answers in the diagram are correct because I did them...

Homework Statement Given a basic circuit of a voltage source and two diodes in series: D1 is .7v @ 10mA D2 is .6v @ .1mA If I is 1mA, What is the voltage across the two diodes? Homework Equations VT~.026 Vt= 60log (I(t)/Is I1 produces V1 I2 produces V2 so V2 = V1 + 60(mV)[log...

Hi, I am stuck trying to work out a problem involving two ideal diodes. http://img200.imageshack.us/img200/668/idealdiodev.jpg I need to find V and I. Aswell as which diode is on and off. I have tried to solve it by assuming d1 is on and hence V is 0 but i can't get the right...

http://img42.imageshack.us/img42/2461/49889005.th.jpg My question is, why does the dc voltage vary with time in this way? Ply it is something to do with the diode allowing current to flow when it has 0.7V or more across it, allowing the capacitor to charge, and when the voltage drops to...

Diode ac and dc resistance? here is my question ...saturation current of a silicon diode is 2uA.and forward current is 20mA...i want to find out the AC and DC resistances of the diode in 300k... so i know that , I(forward)=I(saturate)[exp(eV/nKT)-1] ..so by differentiating both sides...

Homework Statement A diode with reverse saturation current of 1pA and an ideality factor of 1.15 is connected in series with a resistance of 200ohms and connected to a 5V DC supply voltage. Find the current flowing in the diode at a temperature of 290K? How does the current change when a...

I am NOT trying to solve this as a homework problem, I'm just trying to dig out basic concepts that I'm missing when using this battery+resistance diode model.I'm having trouble seeing why, when solving for current, KCL equation does NOT work out as: 1) I= (0-Va)/rd 2) I=(Va-(-5))/R...

I am looking for the simplest possible derivation of the diode equation. I need it to reference to it in my advanced higher project. Basically I have to dissect it. I unfortunately don't know how to derive it and I can't find one simple enough to use. This is what I am trying to end up with...

Hi guys, I have a very simple question but which is messing with my mind. I'm trying to figure out the voltage drop across a diode when it is reverse biased, and I'm just not getting anywhere. Can someone please take a look at the attached image and explain to me what the voltage drop across...

hello all I am new here so i don't know if this is the correct place for this topic so sorry for any inconvenience caused. this is my question: Use the small-signal model of the diode to predict the output voltages for the input voltages given. Plot a graph of | vout(t) | based on the small...

I have trouble getting my head around Zener Diodes. If you reverse bias them, and apply a current, it will not conduct until the applied voltage reaches the Zener Voltage. Am I to understand that no matter how much voltage (within reason) you apply to the diode, its output voltage will always...

I try to understand why, really, there is no current (except for leakage) when a diode is reverse-biased. I studied several texts, and no one really explains, like for instance this otherwise very pedagogic http://en.wikipedia.org/wiki/P-n_junction#Reverse-bias". How I think: The negative...

I searched but had no luck. Sorry if this kind of thing has been answered a bunch. I'm designing a circuit for my car. If you want to know more just ask and I will explain. I want to know when I need to use diodes to protect stuff. I have attached a wiring diagram. I know I need diodes D1...

Hi I have been looking through my book, and even online for the answer because I don't understand why this happens, but I can't find the proper answer anywhere...can someone help me? Thanks.

Hi I have been looking through my book, and even online for the answer because I don't understand why this happens, but I can't find the proper answer anywhere...can someone help me? Thanks.

I have found the 1D differential equation relating voltage and position for a vacuum diode in the space charge region, which is \frac{d^2V}{dx^2} = constant * V^{-1/2} and I know the solution to be V(x) = V_0 \left(\frac{x}{d}\right)^{4/3} which is found by multiplying both...

Homework Statement Design a “smart” branch with resistors and a diode pair such that the branch resistance drops if the voltage applied on the two ends of the branch is too high, and vice versa, (i.e., the branch resistance increases if the voltage applied on the two ends of the branch is...

There are a lot of resources out there which mention that when a diode is forward biased the majority carriers at the n-type material will move to the p-type material "through" the holes therefore the holes will move from the p-type region to the n-type region. However, this doesn't make any...

Ideal diode questions final soon urgent help its actually an example in my book (sedra and smith, 5th ed) which i fail to understand completely! Question: the question is : Assuming the diodes to be ideal find V and I in the circuits. I obviously went through the example but it totally...

Can anyone explain about or point me to any articles about using transistors as zener diodes ? Why not just use zeners, and what connections (c-b short or e-b short) and their pros and cons ?

I am using 1N5226BT/R zener diodes (3.3 Vz, Zz = 28 ohms) and am having trouble getting a constant voltage source... Silly me, I designed a circuit assuming zener diodes would act ideally... According to the datasheet the minimum voltage reverse breakdown voltage would be 3.1 V. Here's what...

Hi All Anyone know where I might find the IV curve for a General Electric BD-5 tunnel diode? I have found a few short datasheets for the BD series, but I really need a curve. Does anyone know where to find such a thing? Or should I just get the SourceMeter out and make one myself...

Greetings, I am an electronic engineer doing some research on high power laser diodes. The problem I try to solve needs ~2300W of optical peak power coming from a high power laser diode. The pulses must be with very long (30ms) at very low repetition rates (2Hz). So,the duty cycle is...

folks, when a pn junction diode is formed, electrons in the n type and holes in the p type diffuse. agreed. then how immobile ions are formed at the vicinity of the junction leading to depletion region? how these immobile ions prevent further diffusion? it is being said electrons and holes...

Homework Statement Explain why the BC junction will give a smaller voltage drop, and will thus have a higher voltage measured then a BE Junction. Homework Equations N/A The Attempt at a Solution Okay, hopefully this is the right section to post this in. See, I have read the book...

Homework Statement I'm trying to calculate what voltage change will compensate for a temperature change of 1 degree for a diode. I have set up the circuit, taken down results and plotted the graph (its non-linear). So I re-plotted it using natural logs of I, and got a straight line with a...

Homework Statement Determine reverse sat current of diode. To show and explain approach. Given-IV characteristics of diode and tabulated values for forward bias voltage from 0-0.8v and corresponding current values. Homework Equations At which point do I need to consider to find the...

Hi guys, I'm trying to find a reliable formula for calculating the depletion depth in a PIN diode at a given voltage and knowing the doping of the layers. Does anyone have one? Formulae for the PN diode are common, but don't apply to the PIN directly as far as I can see. I found a formula...

Homework Statement Hi, I need to produce a linearized equation of the following, I = D. V. exp(-V/B) eq(1) I is the current V is the voltage D is a constant B is a constant Data was collected in an experiment designed to investigate the characteristics of a...

Hey all, I have a diode clamper (1 diode) and I had to use a capacitor in lab to smooth out the output (the input was a triangle wave - without the capacitor the output was still a bit triangular at the tips). This is just curiosity - can anyone explain to me how the capacitor managed to smooth...

When a DC coil (relay) is denergized, shouldn't the collapsing field cause a current that would oppose the change in current? Wouldn't that induced current be in the same direction as when the coil was enegized? Not seeing how a freewheeling doide gets forward biased. If I apply Lenz Law...

Greetings: I recently made my first prototype surface mount board. In designing it, all the SMT components were foriegn to me. I'm a ME, not and EE and my projects are fairly straightforward microprocessor based designs. I chose components similar to old standbys I've used with through hole...

http://optics.ph.unimelb.edu.au/atomopt/publications/littrow_rsi_vol72_p4477_2001.pdf The picture of the ECDL I explain can be found from the above web site. The purpose of piezo is to change the cavity length of the diode laser, so that the wavelength can be varied. From the picture...

What would happen if u had a circuit that was earthed at a point and it had an EMF of let's say 9V. If i had 1 resistor and immediately after that i had a resistor and diode in parallel, would any current enter the resistor. My understand is that it wouldn't since once the diode opens up, it...

Homework Statement A Light emitting diode (LED) drives a single mode waveguide that is 10 km long, and has a material dispersion of – 100 ps/km/nm for wavelengths near 800 nm. The LED radiation has a spectral width of 60 nm and is centered at 800 nm. a) If the LED is pulsed on and off in...